Enhanced Performance of Dye-Sensitized Solar Cells by Lanthanum Doped-TiO2 Photoelectrodes

Dye-sensitized solar cells (DSSCs) are a type of thin-film solar cell in which metal oxide nanomaterials are used as photoanodes. With the aim to improving the efficiency of DSSC, pure and La3+ doped-TiO2 nanoparticles were synthesized by sol-gel method and the quality of synthesized materials was investigated through various characterizations like structural, elemental, morphological and optical studies. The XRD pattern revealed the presence of anatase-TiO2 phase. The FESEM results evidenced the spherical nanoparticles with less agglomeration. The UV-Vis spectra showed enhanced light absorption with the addition of La. With the addition of La, the band gap energy of the TiO2 nanoparticles reduced from 3.06 to 2.72 eV. These nanoparticles were integrated as photoanodes in DSSC and the photocurrent density-voltage (J-V) measurements were carried out. The highest energy conversion efficiency (eta) of 4.75 for pure TiO2 device was achieved while 5.8% was obtained for the 5% La-doped TiO2 device. This enhancement of eta confirmed that 5% La-doped TiO2 is highly suitable for DSSC device fabrication. It was also observed that the high efficiency (similar to 5.8%) with the highest current density of 11.11 mA/cm(2) - was retained even under low-light conditions.